Method and apparatus for mounting electrical components that employs a compensation element

ABSTRACT

An mounting apparatus for mounting an electrical component onto a substrate of an electrical assembly. The mounting apparatus employs a compensating element to facilitate the component mounting operation. The compensating element includes a spring member and a damping member. The spring member applies an optimal contact pressure for securely mounting said component without damaging the component. The damping element acts to damp the spring member during so as to effectively reduce a spring force that acts on the mounting apparatus during the component delivery stage.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and apparatus for mounting componentsonto substrates of an electrical assembly. In particular, the presentinvention relates to the mounting of electrical components onto printedcircuit boards wherein the method and apparatus for mounting suchcomponents includes a compensating element that facilitates an optimalcomponent mounting operation.

2. Description of the Prior Art

U.S. Pat. No. 5,285,946 discloses an apparatus for placing electricalcomponents onto the surface of printed circuit boards. The apparatusincludes a suction pipette tip that is spring mounted onto a retainingdevice. This spring-mounted feature results in a cushioning effect thatprovides the required contact pressure which is necessary for placingthe components onto the substrate, while not damaging the electricalcomponent.

However, the spring-mounted feature may not work as effectively when theelectrical component is supplied or delivered to the mounting apparatusby a known component delivery or supply mechanism. During the deliveryor supply of the components to the mounting apparatus, a substantialamount of force may be exerted onto the electrical component due to thespring-mounted feature of the retaining device which operates toretrieve the component from the delivery mechanism. This force may be sogreat that the electrical component is dropped from the retainingdevice, such as, a suction pipette. If an electrical component isdropped during the delivery of the electrical component to the mountingapparatus, the mounting operation of this specific electrical componentmust be repeated. In addition, the dropped electrical component wouldnecessarily remain in the mounting apparatus and thus may fatally effectthe operation of the mounting apparatus due to errors that may result inthe movement of the mounting heads or substrates.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a method andapparatus for mounting electrical components onto substrates ofelectrical assemblies that provides an effective and optimal delivery ofthe electrical components from a delivery mechanism. In addition, thepresent invention supplies an effective and optimal contact pressurethat is exerted onto the electrical components as it is delivered fromthe delivery mechanism or mounted onto the substrate during thecomponent mounting operation.

The present invention includes a retaining device that employs acompensating element to meet these objectives. The compensating elementessentially has two members—a spring-type member and a damping member.The spring-type member compensates for the thicknesses of a variety ofdifferent substrates and components by generating a contact pressurethat is effectively applied during the component mounting operationwithout resulting in damage to the substrate or component. In addition,the damping member acts to effectively damp or compensate for the forcethat is exerted by the spring-type member during the component deliverystage. In this way, the retaining device is less likely to drop thecomponent during the delivery stage because the this force iseffectively reduced to an amount of force that is less than thatgenerated by a freely oscillating spring.

In an embodiment, the damping member is a shock absorber-type.

In an embodiment, the force due to the delivery of the component actsdirectly upon a first end of the retaining device that faces towards thedelivery mechanism.

In an embodiment, the damping member includes a coupling member thatacts to acts to couple the retaining device to the mounting headdepending on the position of the retaining device relative to themounting head. The coupling member is engaged or disengaged by a controlunit that allows for the precise and controlled coupling of therestraining device to the mounting head. The coupling member acts tosecurely couple the retaining device to the mounting head as themounting unit apparatus acts to receive the electrical component fromthe delivery mechanism. In turn, the coupling elements acts to decoupleor disengage the retaining device from the mounting head so that thespring member can apply an optimal spring contract pressure to thecomponent for mounting the component onto the substrate.

In an embodiment, the coupling member include vacuum coupling, magneticcoupling, friction coupling or mechanical coupling member.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a retaining device that employs a compensatingelement prior to the component delivery stage.

FIG. 2 is a side view of a retaining device of FIG. 1 during thecomponent delivery stage.

FIG. 3 is a side view of a retaining device that employs a spring andcoupling members prior to the component delivery stage.

FIG. 4 is a side view of a retaining device of FIG. 3 during thecomponent delivery stage.

FIG. 5 is a side view of a retaining device that employs a shockabsorber-type and spring members prior to the component delivery stage.

FIG. 6 is a side view of a retaining device of FIG. 5 during thecomponent delivery stage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, an electrical component mounting device or apparatus includesa retaining device that is depicted as a suction pipette 1 for receivingan electrical component 2 from a delivery mechanism 8. The suctionpipette 1 holds the component 2 via a suction force. However, thepresent invention is not limited by the use of a suction pipette thatutilizes a suction force and applies to other like retaining devicesthat utilize other like forces, such as, frictional forces, for mountingthe electrical component by receiving, transporting, and subsequentlyplacing the electrical component onto a substrate of an electricalassembly.

The suction pipette 1 is coupled to a mounting head 4 of the componentmounting apparatus which is not illustrated in detail. The suctionpipette 1 includes a suction pipette first end 3 that is directedtowards the electrical component 2. At least a portion of the suctionpipette first end 3 is connected to the mounting head 4 via acompensating element 5. When the suction pipette 1 contacts theelectrical component 2, the compensating element 5 of the suctionpipette 1 acts to apply a contact pressure to the component 2 so that itis not damaged. The compensating element 5 has a spring type member thatallows for the contact pressure to be adjusted depending on the varyingthicknesses of a variety of different components.

During the component delivery stage where the electrical component 2 isdelivered or supplied from the delivery mechanism 8 via the suctionpipette 1, the suction pipette first end 3 is securely coupled to themounting head 4 as illustrated in FIG. 2. As a result, the force due tothe compensating element 5 is effectively reduced by a damping member toprevent the retaining device 1 from dropping the component 2. Byeffectively reducing the undesirable effects of the force due to thecompensating element 5, the retaining device 1 will securely hold thecomponent even under an increased speed at which the mounting head 4drives the retaining device 1 during the component delivery. In thisway, the component delivery rate can be effectively increased tofacilitate an optimal component mounting process.

An alternative embodiment is demonstrated in FIGS. 3 and 4 wherein thecomponent mounting apparatus employs a compensating element thatincludes a spring 6 and coupling members 7. The suction pipette firstend 3 is coupled to the mounting head 4 via a spring member 6. Inaddition, a coupling member 7 engages the suction pipette end 3 and actsto dampen the undesirable effects of the spring member 6 during thecomponent delivery as previously discussed. The engageable couplingmember 7 operates by vacuum coupling, friction coupling, magneticcoupling, mechanical coupling, or other like coupling principles. Themechanical coupling can be achieved by a piezo element or other likemechanical coupling element.

When the suction pipette 1 contacts the electrical component 2 that ispositioned in the delivery mechanism 8, a definite and precise contactpressure is applied to the component 2 that corresponds to the tensionthat is exerted by the spring member 6. Upon delivering or lifting theelectrical component 2 towards the mounting unit, the engageablecoupling elements 7 are activated wherein the spring 6 remains in acompressed state as illustrated in FIG. 4. As a result, the force of themounting head 4 acts directly onto the electrical component 2 as thecomponent is moved away from the delivery mechanism 8. As the force ofthe mounting head 4 decreases, the damping effect of the coupling member7 on the spring member 6 is then minimized.

After the component delivery stage, the electrical component istransferred to a desired or predetermined position on the substrate andthen subsequently mounted onto the desired position again under theinfluence of the spring member 6 that utilizes an optimal contactpressure depending on the thickness of a variety of different substratesand components as previously discussed in order to ensure that thecomponent is not damaged.

In an embodiment as depicted in FIGS. 5 and 6, the component mountingapparatus includes a compensating element that has a spring and shockabsorber-type member. The spring and shock absorber-type members of thecompensating element act to facilitate an optimal component mountingoperation as previously discussed.

Although modifications and changes may be suggested by those skilled inthe art, it is the intention of the inventors to embody within thepatent warranted hereon all changes and modifications as reasonably andproperly come within the scope of their contribution to the art.

We claim as our invention:
 1. A method of mounting an electricalcomponent onto a substrate of an electrical assembly comprising thesteps of: providing a component mounting apparatus that includes amounting head member, a retaining device attached to said mounting headmember and a delivery mechanism for supplying an electrical component,said retaining device including a compensating element; securing saidelectrical component of said delivery mechanism to said retaining deviceby applying a contact pressure of said compensating element; liftingsaid electrical component from said delivery mechanism by moving saidretaining device away from said delivery mechanism wherein a springmotion of said compensating element is damped; transferring saidelectrical component to a predetermined substrate position of saidsubstrate; and depositing said electrical component onto saidpredetermined substrate position by applying said contact pressure ofsaid compensating element.
 2. A method according to claim 1 wherein saidcompensating element comprises a spring member and a coupling member. 3.A method according to claim 1 wherein said compensating elementcomprises a spring member and a shock absorber-type member.
 4. Anapparatus for mounting a component onto a substrate of an electricalassembly, comprising: a mounting head member and a retaining deviceattached to said mounting head member for mounting said component ontosaid substrate, said retaining device including a compensating elementthat has a damping member and a spring member, said spring memberincluding a spring contact pressure and a spring force; a componentdelivery mechanism attached for delivering said component to saidmounting head member during a component delivery stage; said retainingdevice securely attaching to said component during said componentdelivery stage by applying said spring contact pressure, said dampingmember damping said spring member when said component is moved away fromsaid delivery mechanism so as to effectively reduce said spring force,and said retaining device transporting said component to a predeterminedsubstrate position of said substrate for depositing said component ontosaid predetermined substrate position by applying said spring contactpressure.
 5. An apparatus according to claim 4 wherein said dampingmember comprises a shock absorber-type member.
 6. An apparatus accordingto claim 4 wherein said damping member comprises a coupling member. 7.An apparatus according to claim 6 wherein said coupling member comprisesa vacuum coupling element.
 8. An apparatus according to claim 6 whereinsaid coupling member comprises a friction coupling member.
 9. Anapparatus according to claim 6 wherein said coupling member comprises amagnetic coupling member.
 10. An apparatus according to claim 6 whereinsaid coupling member comprises a mechanical coupling member.
 11. Anapparatus according to claim 10 wherein said mechanical coupling membercomprises a mechanical coupling piezo element.
 12. An apparatusaccording to claim 4 wherein said retaining device further comprises afirst retaining end for mounting said component and wherein said dampingelement acts to effectively reduce said spring component delivery forcethat acts on said first retaining end when said component is removedfrom said delivery mechanism.
 13. An apparatus according to claim 4further comprising a damping control unit for controlling said dampingmember.